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Pigeons were first exposed to a schedule providing food when the time between successive key pecks (the interresponse time) exceeded a specified duration. When food then was presented at regular intervals independent of responding (fixed‐time schedule), responses typically occurred at a steady rate in the periods between successive food presentations. Once the birds had been exposed to a fixed‐ratio schedule, however, response rate under fixed‐time schedules was positively accelerated. Variations in the sequence of conditions given different subjects indicated that the changes in patterning were due to the fixed‐ratio schedule, rather than to the number of transitions from a response‐dependent to the response‐independent fixed‐time schedule, to changed parameter values, or to prolonged experience with the fixed‐time schedule. The effects of fixed‐time schedules on patterning depended upon experimental history.

Pigeons were trained to respond to two stimuli on the wavelength continuum, 550 nm and 570 nm, each correlated with an independent schedule of reinforcement. The multiple schedule component in effect during 550 nm (SI) was always a variable‐interval 1‐min. During the 570‐nm stimulus (S2) the second component of the schedule was either variable‐interval 30‐sec, 1‐min, 2‐min, 5‐min, or extinction for different groups of birds. Generalization gradients were obtained after this training, with the following results: (1) response rate to SI during training was related to the reinforcement frequency associated with S2; the distribution of responding during generalization testing was a function of the schedules of reinforcement used during training and the response rates they produced. Decreases in the relative frequency of reinforcement correlated with S2 resulted in increases in the distribution shift of responses away from S2 during generalization testing.

Three pigeons with a history of attacking a mirror target, and two of six pigeons with no prior exposure to targets, attacked a colored photograph of a conspecific during exposure to intermittent schedules of reinforcement for key pecking. Rate of attack on the photograph decreased when the reinforcement schedule was removed. The topography, temporal pattern, and locus of attack on the picture were comparable to schedule‐induced attack on live, stuffed, and mirror targets. When silhouette, outline, and plain paper targets were used, schedule‐induced attack was more sensitive to a change in target characteristics with a concurrent target‐preference procedure than with an analogous successive‐testing procedure. The combined results of the two testing procedures indicated that an “upright” white‐on‐black silhouette of a pigeon with or without an eye was more effective in controlling attack than was a comparable “inverted” silhouette, an outline of a pigeon, or a piece of colored paper.

Pigeons were trained on multiple schedules in which a fixed number of pecks produced either a fixed or a variable period of access to food, the average variable‐duration reinforcement equalling the fixed. Pecking rates were generally higher during the variable‐duration component. Subsequent performance on concurrent schedules revealed an initial preference for variable‐duration reinforcement for all subjects; for most subjects, this preference was sustained. For one subject, the average variable duration was gradually reduced to half the fixed duration: continued preference for the variable component resulted in a loss of up to 30% of available reinforcement time. A return to multiple schedules with unequal pay‐off shifted the preference to the greater fixed duration, and this preference was maintained even when the variable duration was again raised to equal the fixed duration. For the remaining subjects, the initial variable‐duration preference on concurrent schedules was gradually replaced by a side preference. When the range of variable durations was varied, keeping the average variable duration equal to the fixed, the occasional longer reinforcers sustained a preference for variable‐reinforcer durations for three of the four subjects.

Six homing pigeons were trained on a variety of concurrent‐chains schedules in which the initial links were equal variable‐interval schedules and the terminal links were fixed‐interval schedules. Both terminal‐link and initial‐link schedules were systematically varied. The results showed that preference for a particular terminal‐link schedule combination was greater, the shorter the initial‐link schedules. The data closely matched predictions from the model of choice suggested by Davison and Temple (1973), but did not match predictions from two other models. An alternative method for analyzing concurrent‐chains performance by assuming that the schedule consists of both chained schedules and successive, discriminated components that comprise multiple schedules, was suggested.

Pigeons were trained on three‐key concurrent chain schedules in which the initial links were variable‐interval schedules and the terminal links were fixed‐interval schedules. In the first experiment, the initial links were all equal and the terminal‐link schedule on one key only was varied. In the second part of the experiment, the terminal‐link schedules were all fixed, but different, and the initial‐link schedule on one key was varied. Relative response rates in the initial links did not match either the relative arranged, nor the relative obtained, terminal‐link reinforcement rates. The relations between independent and dependent variables in three‐key concurrent chains were similar to, but not identical with, those found in two‐key chains comprising the same schedule types.

Two experiments were conducted demonstrating that under certain conditions pigeons may peck at a higher rate on a key that produces intermittent reinforcement following a delay than on one that always produces reinforcement following the same delay duration. In both experiments, concurrent chain schedules were employed. In Experiment I, a single peck on one key led to a white light and a delay of 15 sec, which always terminated with food. A peck on the other key led to its illumination by one of two colored lights and a delay period of 15 sec. The delay was followed by either food presentation or timeout, either one lasting 3 sec. In a control group, the lights on this key were not correlated with food or timeout. Under the correlated stimuli, birds more often pecked the key leading to intermittent reinforcement, whereas with uncorrelated stimuli they pecked the key leading to the white light and 100% reinforcement. In Experiment II, concurrent variable‐interval schedules were employed in the first link. The results showed generally that the relative rate was higher on the key leading to intermittent reinforcement when the stimuli were correlated with reinforcement and timeout than on the key leading to 100% reinforcement. There was some indication that this performance was affected by (1) the duration of the delay, (2) the percentage of reinforcement on the key yielding the higher percentage of reinforcement (the key with the white light), and (3) prior experimental conditions.

Key pecking was reinforced on a two‐component multiple schedule. A variable‐interval schedule controlled reinforcement in both components. During one component, access to reinforcement was preceded by a tone; Final Acceptance in the other component, a standard unsignalled schedule was in effect. After performance stabilized, subjects were given a choice between the signalled and unsignalled schedules. They were placed in the chamber with the unsignalled schedule in effect on the right key. A single response on the left, or changeover, key produced the signalled schedule for 1 min. Both pigeons in Experiment I pecked the changeover key at a rate sufficient to remain under the signalled schedule for over 90% of the session. Removing and reintroducing the tone demonstrated that the changeover‐key responses were due to the occurrence of the tone. In Experiment II, when pecking the changeover key produced the unsignalled schedule, pecking the changeover key declined. The results may be explained either in terms of Hendry's information hypothesis or as escape from an intermittent positive reinforcement schedule.

Three retarded subjects and two developmentally normal toddlers were trained using imitation and reinforcement procedures to use correct sentences. The experimental task was to use sentences with correct subject‐verb agreement to describe pictures that were presented to the subjects. Two classes of sentences were taught: those involving a plural subject that required the use of the verb “are” (for example, “the boys are running”) and those involving a singular subject that required the use of the verb “is” (for example, “the boy is running”). The basic design of the study involved multiple baselines for each class of sentences. Four of the subjects began to produce novel, untrained sentences of a particular type to generalization probe pictures when that particular class of sentence was currently being trained. Thus, the imitation and reinforcement procedures appeared to be functional in producing generative sentence usage for both types of sentences. One subject produced correct sentences to both singular and plural probe pictures when only “is” sentences had been taught. A reversal procedure and retraining phase indicated that for this subject, imitation and reinforcement procedures for training one class of sentence behavior seemed functional in producing generative responses of the other class of sentences.

Reinforcement techniques of prompting and shaping were employed to develop hand‐waving, a useful social greeting response, in four institutionalized retarded subjects. A multiple‐baseline design across subjects demonstrated the reliable functioning of the training procedures. Specifically, it showed that training and maintenance of the greeting response by one experimenter was not usually sufficient for generalization of the response to the more than 20 other members of the institution staff who had not participated in the training of the response. However, high levels of generalization to staff members were recorded for three subjects over periods ranging from one to six months after a second experimenter trained and maintained the response in conjunction with the first experimenter. The fourth subject, although never receiving training by a second experimenter, showed similar results following a second training by the first experimenter.